This invention relates to vegetation cutters and has particular reference to cutters that cut by means of a filament or strip that is rotated rapidly about an axis that may be either substantially vertical or substantially horizontal, depending upon the application.
In most filament cutters, the cutting filament or strip is stored on a spool or reel from which a cutting length extends. During use, wear on the cutting length shortens that length, and it is then necessary to withdraw filament or strip from the spool to make up the cutting length to its working value. The filament cutter is supplied with a reel or spool on which a supply of filament or strip is stored.
In general, when the supply of filament or strip on a reel or spool is exhausted, the empty reel or spool is removed and a replacement reel or spool, with a new supply of filament or strip already loaded is fitted. This is a simple operation, which is carried out by the operator of the vegetation cutter. The replacement reels or spools are readily available from the usual retail sources, including for example, retailers of the vegetation cutter itself.
The cutting filament or strip is a flexible, generally non-metallic filament or strip, in particular a light weight plastic filament or strip, having a relatively small diameter, which is adapted to cut or trim grass or other lightweight vegetation with reasonable effectiveness, and which is unlikely to cause significant injury to persons or animals struck by the flailing filament or strip.
During manufacture of the reel or spool with the supply of cutting filament or strip wound on it, the cutting filament or strip has to be wound onto the empty reel or spool, either manually or automatically. As the winding of a length of cutting filament or strip is commenced, it is necessary for the free end of the filament or strip to be secured, at least temporarily, to the reel or spool before the winding operation can be commenced.
As the filament cutter is used, and the supply of filament or strip becomes exhausted, a relatively short length of filament is eventually left on the spool. If the end of this short length, which is of course the free end referred to in the preceding paragraph, is not secured to the spool, then there is a danger that a length of filament or strip, which might be of a similar length to the cutting length, or may be even longer, may fly off from the cutter head, giving the risk of injury to the operator.
A number of proposals have been made to provide a means of securing the filament or strip to the reel or spool for winding, but none of these is entirely satisfactory. It has been proposed, to locate the free end of the thermoplastic line in an aperture in the spool wall, and optionally to deform the free end by heating, so that it is retained within the spool. This method has the disadvantages firstly that it requires the provision of a heating element at the winding station, and also may lead to environmental and safety issues associated with the heating of plastics materials and secondly that the final section of line is not retained on exhaustion. In GB 1,576,172 it was proposed to thread the cutting line through an aperture in the spool wall and then to secure it by knotting, which involves an inconvenient mechanical operation; an alternative proposal in the same specification suggests that the line can be embedded in the spool wall, but no details are given of this proposal.
It has also been proposed to provide two closed apertures in one flange of the spool and to feed the end of the line through each of these apertures prior to commencing winding. While effective, this proposal has the disadvantage that the initial feeding of the line into the apertures prior to winding must be carried out in the opposite sense to the winding, and therefore constitutes an additional operation in the winding process, adding to the manufacturing costs.
UK Patent No. 1,582,568 discloses a filament cutter in which the filament is stored on a disk having a series of apertures circumferentially therearound, with a length of filament fixed to the disk and having a terminal length thereof extending from one of said apertures as a cutting length of the filament. Successive apertures define intermediate portions of filament which themselves become terminal lengths as the line is consumed.